Many businesses and postal services utilize high speed mail processing machines to rapidly process and/or transport collected mail pieces. Collected mail pieces are placed into mail carrier trays for transportation to a post office. At the post office, these trays must be unloaded, and the mail must be transported to a sorting machine for sorting by addresses.
While there are numerous prior art apparatus for processing mail, there are no known apparatus to receive a series of mail trays containing mail, continuously unload these trays in proper orientation, and then controllably deliver the mail to a desired mail processing machine in a fast and efficient manner.
Tray unloading has long been a manual process. Recently, automated devices for unloading mail trays have been disclosed in U.S. Pat. Nos. 5,906,468 and 5,713,713, both entitled “Pivotal Tray Unloading Apparatus,” issued to Vander Syde et al. on May 25, 1999 and Feb. 3, 1998, respectively, and U.S. Pat. No. 5,772,383 entitled “Pivotal Mail Tray Unloader,” issued to Kalika et al. On Jun. 30, 1998. These patents are all assigned to the assignee of the present application.
The apparatus disclosed in these patents, and in particular the Vander Syde et al. '468 patent, provides for automated removal of mail from a tray, removal of the tray, and placement of the mail on a transport. However, such devices are relatively complicated, having numerous movable components to manipulate the tray, and is relatively time consuming. The tray must be grasped and rotated both front to back and side to side. Further, the tray removal requires numerous movable parts, including pneumatic cylinders. Such multiple movements and parts can result in a relatively lengthy and non-continuous operation, and overall slower processing times. Further, the apparatus could be subject to lengthy down times if any of these components fatigue or fail. Due to the numerous components, this apparatus is relatively expensive to manufacture and maintain. The present invention provides a substantial improvement and advantage over this prior art apparatus.
U.S. Pat. No. 5,271,710 entitled “Device for Loading Articles Onto an Unstacking Magazine and a Loading Method Using this Device,” issued to Decharran et al. on Dec. 21, 1993, discloses a device which assists an operator in the unloading of trays of flat articles. Unlike the present invention, the unloading operation of this device remains mostly manual. The trays are manually moved over a tipping trough in a deck, whereupon the tray is tipped. The deck then tilts to raise the bin so that the articles can slide out of the tray and onto a conveyor. At all times, the operator must use its hands to support and guide the articles and prevent them from falling.
French Patent No. 2,706,331 illustrates an apparatus for unloading trays of flat articles. The articles are standing on edge in the tray, which sits on a conveyor. The tray is then turned on edge sideways, into a holding area. The tray is next removed, leaving the contents in the holding area. Finally, the holding area is pivoted ninety degrees, placing the flat articles back on edge on the conveyor. This device, unlike the present invention, does not re-orient the contents of the tray, i.e., does not turn articles which stacked flat up onto their edge. Further, it appears that this device also remains largely manual in operation.
There are other known devices for removing the contents of a container in industries unrelated to mail processing. Such known devices in general are inappropriate for mail processing applications, where the contents must be precisely handled and positioned. Specifically, the mail which are placed flat in the tray, stacked on top of each other, must be made to stand on edge, and then must be precisely transferred from the unloading apparatus to a conveyor system while being properly supported at all times, without manual intervention. Such known prior art devices cannot adequately achieve the same.
For example, U.S. Pat. No. 2,951,603 entitled “Container Handling Machine,” issued to Preuss on Sep. 30, 1957, discloses a container handling machine, and in particular a machine for unloading fruit from a crate. The machine includes a relatively complicated system of belts and rollers in association with a wheel for inverting the crates. Once inverted, the fruit remains on an inner conveyor belt which surrounds the wheel, while the crate rides up a pair of belts along the sides of the wheel. However, this machine in not suitable for mail processing. The machine does not precisely control and position the contents of the crate. This machine simply inverts the crate and could not orient mail pieces stacked flat up onto their edge. Further, the crate removal belts of this machine extend slightly into the crate, and thus would not function with respect to mail processing, as the belts would hinder removal of the mail from the tray.
Other prior art devices for emptying the content of boxes are used in other industries, for example: U.S. Pat. No. 5,275,523 entitled “Apparatus for Removing Cigarettes from a Package that Encloses the Same,” issued to Stewart et al., which utilizes a pair of wheels to grasp cut open packages of cigarettes and rotates them to a vertical position whereupon the cigarettes fall out of the package, which is then discharged; U.S. Pat. No. 2,735,561 entitled “Box Dumping Machine,” issued to Van Doren on Feb. 21, 1956, which includes a pair of clamping members, movable along a pair of belts, which grasp the box and dump the contents (fruit) as the clamped box travels along the belt path; and U.S. Pat. No. 2,424,252 entitled “Box Dumping Machine,” issued to Orlando on Jul. 22, 1947, which discloses an arm the grasps a box of fruit, then rotates one hundred eighty degrees, during which time the fruit dumps out of the box and down a chute. Again, such prior art devices are wholly inapplicable to mail processing and cannot achieve the advantages and improvements achieved by the present invention.
With respect to spiral transports, there are known devices for a transport system comprising a spiral for transporting paper and other flat articles. Such prior art devices generally fall into one of two groups. The first group is a coil having an end drive. When the end is rotated, the coil rotates therewith. The second group is a helix or screw type drive, having a central shaft extending the length of the spiral transport, from which the helix extends. When the central shaft is rotated, the helix rotates therewith.
Examples of coil transports are disclosed in U.S. Pat. No. 5,544,876 issued to Ruch on Aug. 13, 1996; U.S. Pat. No. 4,378,938 issued to Staniszewski on Apr. 5, 1983; U.S. Pat. No. 3,377,929 issued to Ware et al. on Apr. 16, 1968; U.S. Pat. No. 2,826,413 issued to Brodie et al. on Mar. 11, 1958; U.S. Pat. No. 2,778,638 issued to Whillock et al. on Jan. 22, 1957; U.S. Pat. No. 2,048,870 issued to Kannee on Jul. 28, 1936; U.S. Pat. No. 1,576,243 issued to Mentges on Mar. 9, 1926; U.S. Pat. No. 277,806 issued to Stonemetz et al. on May 15, 1883; and in German Patent Application No. DE 2330225 A1 issued Jan. 9, 1975.
The problem with known coil transports is that they cannot operate at very high speeds or over any great length. These coils are typically supported only at the drive end, so that the exit end remains open or unimpeded for the article to transfer out of the coil. Thus, the length of the coil is limited by the structural integrity of the coil itself, and as such must remain relatively short. Further at relatively high speeds, due to the unbalanced nature of the coil, these coils begin to vibrate, shake or otherwise move in an undesirable manner and even break up or fatigue, thus becoming ineffective or inoperable. The present invention, however, overcomes these limitations, allowing for any length coil to be drive at high speeds by its novel driving means.
Examples of helix transports are disclosed in U.S. Pat. No. 5,271,710 issued to Decharran et al. on Dec. 21, 1993; U.S. Pat. No. 4,884,795 issued to Vander Syde on Dec. 5, 1989; U.S. Pat. No. 4,875,309 issued to Long, III on Oct. 24, 1989; U.S. Pat. No. 4,432,540 issued to Akers et al. on Feb. 21, 1984; European Patent Application No. EP 0947453 A1 published on Oct. 6, 1999; French Patent Application No. FR 2727948 A1 published on Jun. 14, 1996; PCT Patent Application No. WO 90/12745 published Nov. 1, 1990; United Kingdom Patent Application No. GB 2020613 A published Nov. 21, 1979; and United Kingdom Patent No. GB 1524306 published Sep. 13, 1978.
These known helix or screw type transports generally suffer from some of the same problems as the coil transports. While the length can be longer, it is still limited, even where the screw is supported at two ends. At high speeds, these transports are unbalanced and start vibrating or suffer other undesirable movement which can jeopardize the structural integrity of the screw conveyor. Additionally, the central shaft can interfere with the articles being transported, or otherwise prevent or limit the articles from more fully entering the helix. Again, the present invention overcomes these limitations.
Accordingly, there is a need for a method and apparatus for high speed mail tray unloading and mail transporting in a smooth, efficient and continuous manner. The present invention fulfills such a need.